In recent years, still images and video content are widely provided using FLASH on various types of webpages (JP2004356998A (PTL 1)). Image data rendered with FLASH is described in Small Web Format (SWF), which consists of vector data. An original format is used for SWF format vector data. Specifically, SWF format vector data specifies video data with a plurality of line segments, the starting point (MoveTo) and ending point (LineTo) of each line segment, and the fill styles (Fillstyle) to the left and right of each line segment. The fill style refers to a pattern for filling space, such as filling with a pale color.